I smell a rat somewhere... someone hasn't checked the numbers!

New homes built to the 2022 Scottish building standards need almost no heating, a kW or two, it wouldn't be economic to lay gas mains and fit boilers for such low heat demand. If they do have say 5kW heat pumps (over sized) then 1.5kW electricity supply each will be plenty, so 1.5 MW for every 1000 houses. Heating is not what they want 35 MW of electricity for!

Possibly they are thinking about electric cookers (10kW per house) or car chargers (7 kW, but not everyone at once)?

This story allows the Telegraph to bash both heat pumps and the SNP all at once, so I wouldn't expect arithmetic to stand in the way!

Edit: and that development started building way back in 2012, it wasn't held up by some unforeseen electricity supply problem with boilers in 2024. Sounds like someone screwed up and is looking for imaginative excuses to ask for more money!

Undoubtedly true and needs changing, but that's not a problem caused by heat pumps or fixed by gas boilers.

And even if they used 3x or 5x more heat than the law requires, they still wouldn't need 35 MW of electricity for heating their housing development. If you put 35MW of electricity into heat pumps, you get 100 MW of heat out, enough for a whole town.

The volume housebuilders are well known for taking any chance to protest against heatpumps, insulation, airtightness, or any rules at all (as Jonti said) - I wouldn't believe anything they say as 'reasonable sources'!

MW is the same as MVA if we have pf=1 (which we should) - sometimes a little different for industrial sites with big induction motors. Yes indeed the actual load will be less than 1.5MW per 1000 homes, because not everyone will be running their heatpump flat out at the same moment.

An 80A supply is 18.4 kW , which is plenty for a 7kW EV charger to run simultaneous with a 5kW heat pump (IE 1.5kW electric draw) and also a cooker, kettle, and a hundred lightbulbs and a huge TV.

Many (most?) EV chargers now come with a current clamp that goes on your mains, so if you are getting close to 80A it will slow down charging the EV a bit. Also comes with a timer to charge the EV overnight when the other loads are off.

Housing is often held up getting utility connections, usually drains and sometimes electric. Has always been so, is nothing to do with heatpumps in 2024, despite what the Telegraph prints!

I believe that since 2022 all chargers sold must have the capability to delay or reduce charging when instructed by the electricity supplier. So I think their demand can be levelled easily now.

It's conceivable that heat pumps could be required to have similar control capability, so their demand could be similarly levelled, though not at present.

Cookers come in various types, but just considering induction hobs, ours has a c 40 A, 10 kW max demand and it would be difficult to legislate against them all being used at once. Similarly some firms (I'm looking at you Neff) produce hobs that are limited to 13 A demand but I can't imagine them being made compulsory. Running a wok would be very difficult, although I know some who do. At that sort of level we're probably back to the classic maximum load of a gazillion kettles being turned on at half time in a football match.

That SP Networks ADMD calculation is weird. They add up various things and average them in a complicated way when what they're really doing is just totalling the demand and dividing by the number of houses. All the kerfuffle in the middle to get an 'average' is just a waste of space.

They also use the term 'Heat Pump capacity' exactly once and don't define it. If asked, my first guess would be that meant the output capacity, but from the context I presume they mean the input electrical demand.

Posted By: WillInAberdeenSo for 1000 homes with EV chargers and small heatpumps they'll want (1.5 + 2.5 + 1.5) = 5.5 MW, of which 1.5MW for the heat pumps.

From the item -

The SPF raised the example of a very large housing development being built in Winchburgh, West Lothian that originally required eight megavolt-amperes (MVA) of electricity, before the gas boiler ban was announced.

For the moment let us assume this is correct (I doubt they would try bringing false facts to a committee meeting) this is for 3,400 houses.

So by your calculation, the old figure would be just over 5MVA (1.5 * 3,400)- allowing for infrastructure (there are 2 high schools and a primary school alone) their stated old figure of 8MVA seems reasonable.

At 5.5KVA per house, 3,400 would come out to 18.7MVA a fair bit below their 35MVA, but still a significant increase.

They may be enhancing their argument, but the basis, that they need a much bigger grid connection, isn't wrong and it may well be that the grid cannot supply it.

*showers

Seems some DNOs are standardising on 80A supplies now, and replacing existing 100A supplies with 80A. There's apparently some tolerance in the fuse to supply up to 100A for several hours (23kW), so no problems with the electric shower and cooker running at the same time.
https://www.linkedin.com/pulse/uk-electricity-networks-need-rapidly-sort-heat-pump-standards-lowes



Another cracking anti-heatpump story in the Telegraph today, heat pumps are all apparently a Chinese plot to control the world with Putin! Wondering if they're using AI bots to write this stuff.

Can't find it now but was reading a while back that 'PV is a problem' (a change from blaming 'heatpumps and EV chargers'!) The story was that DNOs used to set their transformers up at 253V to overcome cable resistances during peak winter demand, so the supply would still arrive at the homes within legal tolerance of 230V±10%. But then if everyone is exporting PV, the voltage in the homes goes above 253V on a sunny day. So the transformer voltage setting has to be reduced and then cannot deal with peak winter power demand.

Posted By: ArtiglioMy house had a 60amp fuse when i moved in

That's a typical connection for an electrically heated house in France - the maximum monophase connection offered, I think. For those on gas, it's typically 30A. Around 70% of all domestic properties, including apartments, have a 30A connection.

That's low compared to the UK for 2 reasons:
- the power chosen determines the standing charge, so there's an incentive to keep it low (a 60A connection costs in the region of €19/month, 30A around €12.50, down to €9.25 for the minimum 15A supply)
- a load-shedder can be fitted to the consumer unit that temporarily disconnects one or more selected low-priority loads (water heating, central heating, washing machine, etc.) if the total load approaches the maximum - for example while fully using an electric hob.

Because France relies much more than the UK on electric heating, it has a much higher electricity demand (around 50% more) - more like the UK needs to become as it transitions away from gas. It may well be that the UK needs to consider a French style charging scheme to help moderate the grid expansion that will be required.

Posted By: WillInAberdeenSeems some DNOs are standardising on 80A supplies now

Posted By: Artigliothere was a push towards making 80amps the norm

Looks like that is now National Grid policy - https://connections.nationalgrid.co.uk/news-and-events/latest-news/standardisation-of-fusing-to-80a

Mike1, cheers , interesting how different places do things. The flats i converted/ built all have 60 amp supplies from a 3 phase supply that was bought into the building then split. That was 20 years ago so things may well have changed. If i am ever forced to heat these buildings with other than gas, as things things currently stand i’d be better off upgrading the insulation on the block built 20 years ago and relying on resistive heating , the other block having been built in 1870 would likely need a communal ashp and attendant distribution and ufh in the flats, but if it ever goes that way it’ll be better to turn it back into one/two larger home/s,(assuming local planning would allow it, ) as i don’t see any realistically economically viable way of getting that building away from gas. It’s not listed but in a conservation area in an area that doesn’t command the high property prices to support substantial investment into the building as it currently is.
If it weren’t for the woodworking 60amps would probably be enough for me ( whilst heating with gas ) unless i put a car charger in , but even then if it were intelligent ( my description) I wouldn’t forsee many problems. My usual consumption is around 8kwh / day , with workshop use on top and even then an enthusiastic day of making shavings and dust might top that out at 30 or so.

I’ve put in extra cabling to enable me to fit an electric boiler or ashp in the future ( for a brief period i bought into the notion that eventually electricity would be so plentiful as to be cheap enough to rely on resistive heating, with a woodstove supplement in cold spells, but have moved away from that occuring in my lifetime) but with the push toward 80 amp supplies , i’m guessing that any request for 100 amp supplies is going to leave the consumer liable for the upgrade costs, for which i see costs in the future will include an infrastructure charge similar to those imposed by the water companies. Which means i’m planning it all around the current going forward.

Owlman - was that new tails from the main fuse or did your upgrade include a new cable from the “road” ?

Posted By: ArtiglioOwlman - was that new tails from the main fuse or did your upgrade include a new cable from the “road” ?

The supply, is from a pole on the opposite side of the road from my property, it passes under the road and into a chamber near my boundary and then under my front garden to the meter box on the house wall.
The contractor dug a hole in the garden to locate the conduit and then split it and installed new tails back to the chamber and forward to the meter box. The total distance is about 25M, give or take. The originals were 16mm and they've been upgraded to 25mm.

Posted By: owlmanHe discovered on pulling the main fuse that the fuse cartridge itself was in fact 80A although clearly labelled as 100A on the outside casing.

Ours is the same, I think that's normal. It means the fuse holder unit can handle up to 100A (80A fuses are the same size and are normally what's fitted). Same as with a 13A plug or FCU that can have a 5A or 3A fuse fitted, the only way to know what's inside it is for the electrician to open up and look!
It would be nice if they put a sticker on it or something to help with planning. If you have an electrical inspection report then the fuse rating might be written on that, if it was opened.